Caption: Killer whale. Dorsal fin and back of an orca, or killer whale (Orcinus orca). This large predatory dolphin is found in seas world wide, except for the extreme polar regions. A killer whale may reach a length of over nine metres, although the female is usually smaller. The dorsal fin of the male may be almost two metres in height. This marine mammal lives in groups of between two and forty individuals, chasing and eating almost anything it comes across, including seals, fish, penguins, whales and other dolphins. It rarely, if ever, attacks humans. It has no natural predators. Photographed near Johnstone Strait off Vancouver Island, British Columbia, Canada.